Summary of Final Fair Values and Purchase Price Allocation at Acquisition Date of Assets Acquired and Liabilities Assumed (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2014	Mar. 04, 2014	Sep. 30, 2013
Business Acquisition [Line Items]
Property and equipment	$ 2,500	$ 17,600		$ 200
Goodwill	$ 211,045	$ 209,331		$ 201,130
Griffith Energy Services, Inc.
Business Acquisition [Line Items]
Trade accounts receivable			$ 49,010
Inventories			5,143
Other current assets			2,984
Property and equipment			17,263
Other long term assets			1,778
Current liabilities			(31,096)
Total net identifiable assets acquired			89,482
Total consideration			97,650
Less: Total net identifiable assets acquired			89,482
Goodwill			8,168
Griffith Energy Services, Inc. | Customer lists, trade names and other intangibles
Business Acquisition [Line Items]
Intangible assets			$ 44,400